Anti-nuclear-power advocate Gary Headrick, outside the San Onofre plant, urged Laguna to call for a full review of plant operations.

Southern California Edison announced Friday it will permanently close the San Onofre Nuclear Generating Station, which has been shut for more than a year.

“We have concluded that the continuing uncertainty about when or if SONGS might return to service was not good for our customers, our investors, or the need to plan for our region’s long-term electricity needs,” Ted Craver, Edison’s chairman said in a statement.

Gary Headrick, organizer of the San Clemente-based grassroots campaign to keep the power plant offline, gave credit this morning to the volunteers that made it happen. “There were so many people that worked so hard,” he said. “We’ve been laughing and crying all morning.”

Headrick, who heads up the sustainable-living organization called San Clemente Green, plans a celebratory gathering at 10:30 a.m. at the south entrance to the power plant just south of San Clemente.

Edison, operator of the plant for the last 40 years, said today that the uncertainty about when or if the plant would be restarted didn’t make economic sense to customers as well as investors.

As a result of the closure, plant staff will shrink by 1,100 employees to 400 in 2013, subject to regulatory approval, an Edison statement said.

Both of the plants generators have been shut since January 2012; one was shut after a small radiation leak. The leak came from a worn tube that was part of a steam generator installed in 2010 as a routine process.

Friends of the Earth, an anti-nuclear advocacy group, contended that the new steam generator constituted grounds for a license review process that would have opened up the installation to full investigation and public input. The Atomic Safety and Licensing Board, an arm of the Nuclear Regulatory Commission, sided with the environmentalists last month by ruling that the proposed restart of the Unit 2 generator would require detailed public hearings. Laguna Beach, Irvine, Santa Ana and other Orange County cities, as well as Los Angeles, opposed operating the plant either outright or under stringent safety measures.

“I have a great sense of relief. The more knowledge I had about San Onofre, the clearer it became that it shouldn’t start under any circumstances,” said Laguna Beach Council member Toni Iseman.

While Edison said uncertainty over bearing more financial costs drove its decision, Iseman pointed out Laguna and surrounding areas also faced economic threats from the plant’s continued operation. “If Edison had another event, what would that do to tourism in Laguna? From a practical perspective, it’s a huge relief.

“It was a risk we couldn’t afford to have.”

Iseman said she wrote a letter to the NRC, arguing about the risks of restarting San Onofre, which has the industry’s worst safety record. “Why choose to jeopardize the whole industry by turning it back on?” Iseman said she asked in her correspondence with regulators.

Edison requested regulators’ ascent to restart one generator at 70 percent power for five months, a plan under review by regulators and criticized by opponents as risky and without precedent. The plan was based on work done by engineering groups from three independent firms with expertise in steam generator design and manufacturing, Edison said.

Even so, the Atomic Safety and Licensing Board’s ruling created further uncertainty about restarting the plant, Edison’s statement said.

Costs of maintaining the plant and buying replacement power would continue for another year, the utility estimated. “SCE has concluded that efforts are better focused on planning for the replacement generation and transmission resources which will be required for grid reliability,” the statement says.

“Thanks to consumer conservation, energy efficiency programs and a moderate summer, the region was able to get through last summer without electricity shortages,” said Edison’s president, Ron Litzinger, who pointed out the company made transmission upgrades in the last year. “We hope for the same positive result again this year,” Litzinger added, “although generation outages, soaring temperatures or wildfires impacting transmission lines would test the system.”

Full retirement of the units will take years, in accordance with industry practices, and actual decommissioning will take many years, all subject to NRC oversight, Edison says. “I need — and ask for– your continuing support as nuclear professions to ensure we remain as diligent about our responsibilities and obligations as you have demonstrated in in the past,” said Pete Dietrich, an Edison executive, in a letter to employees.

The utility intends to pursue recovery of damages from Mitsubishi Heavy Industries, the supplier of the replacement steam generators, as well as from its insurer. In connection with the decision, Edison estimates that it will record a second quarter charge against its earnings of between $450 million and $650 million before taxes.

San Onofre is jointly owned by Edison, San Diego Gas & Electric and the city of Riverside.